Leather-stretching machine



(No Model.) 3 Sheets-Sheet 1. B. P. BRADFORD.

LEATHER STRETGHING MACHINE.

No. 414,283. Patented Nov. 5, 1889.

N. FETERS. Prwmmm n mr. wamm lnn. D c

(No Model.) I 3 Sheets-Sheet 2. B. P. BRADFORD.

LEATHER STRE'IOHING MACHINE.

No. 414,283. Patented Nov. 5, 1889.

N. PETERS. Phnwuxmkm mr. wasmngwn. D. C.

(No Model.) 3 Sheets-Sheet 3. B. P. BRADFORD. LEATHER STRETUHINGMACHINE.

Patented Nov. 5, 18-89.

UNITED STATES PATENT OFFICE.

BENJAMIN I. BRADFORD, OF WORCESTER, MASSACHUSETTS.

LEATHER-STRETCHING MACHINE.

SPECIFICATION forming part of Letters Patent No. 414,283, dated November5, 1889. Applicatiou filed July 18, 1889. Serial 110,317,917. (Nomodel.)

To aZZ whom it may concern:

Be it known that I, BENJAMIN P. BRADFORD, of the city and county oflVorcester, and State of Massachusetts, have invented certain new anduseful Improvements in Leather-Stretching Machines; and I do herebydeclare that the following is a full, clear, and exact descriptionthereof, reference being had to the accompanying drawings, forming apart of this specification, and in Which Figure 1 represents a top orplan view of a leather-stretching machine embodying my improvements.Fig. 2 is a central vertical longitudinal section thereof, taken on linea a, Fig. 1, looking in the direction indicated by the arrow. Fig. is aview taken through the main shaft, as indicated by line b, show ing theside of the whole machine beyond said line; and Fig. at represents somuch of the opposite side of the machine as is necessary to illustratethat portion of the mechanism for regulating or governing the stretchingcapacity of said machine which comes upon said opposite side of themachine.

The object of my invention is to produce a machine whereby leather, moreparticularly for belting, may be racked or rubbed and stretched byautomatic mechanism in the most perfect manner and at the least possibleexpense; and it consists of a machine having adjustable reciprocatingracking-frames adapted to rub longitudinally upon the under side of theleather to stretch the same, of adjustable means for holding the ends ofsaid leather while being thus rubbed or racked, and automatic mechanismfor taking up the slack as fast as the leather is stretched, as will behereinafter more fully set forth.

In order that others skilled in the art to which my invention appertainsmay better understand the nature and purpose thereof, I will now proceedto describe it more in detail.

In the drawings, the parts marked A represent ihe main frame or bed,having the supporting'legs or standards A and the upright frames A Justunder the bed, inside of the legs and ateach side of the machine, arearranged and secured the guideways or tracks B B, in which the carriageC is fitted to slide forward and back with longitudinal reciprocatingmovements, being thus operated by a crank D on the main shaftE throughthe connecting-rod F, pivoted at one end to said crank and at its otherend to the slidecar-riage. (See Fig. 2.) The main shaft E is fitted toturn in suitable stationary bearings E, and is provided with the usualtight and loose pulleys G G, which may in practice be connected, asordinarily, with suitable driving mechanism. (Not shown.)

Above bed A, at each side of the rear of the machine, are arranged andsecured the longitudinal guideways or tracks H H, in which the carriageI is fitted to slide, as required, to adjust the same forward and back.It may be held against longitudinal movement toward the front end of themachine, for the purpose hereinafter described, by means of verticalholding-pins a, which may be passed down in front of the carriagethrough suitable openings C62 in the guideways or tracks. (See Fig. 1.)Although I prefer this mode of fastening in practice, I do not limitmyself thereto. At the forward end of the machine are similarly arrangedand secured the longitudinal guideways or tracks J J, for the carriage Kto slide in, as and for the purpose hereinafter described.

Upon the reciprocating carriage C, first referred to, are mounted theracking-frames L L, both pivoted at their inner ends to a rigid bearingZ1, extending up from about the center of the carriage. The outer end ofthe frame L is provided with means whereby said end may be raised andlowered conveniently, while the outer end of the frame L is providedwith means for producing a constant upward pressure. By this arrangementthe rear end of the racking-frame may be adjusted to the requiredelevations for treating diiferent lengths of leather, and a constantyielding pressure is produced at the front end' of said leather instretching the same, as hereinafter and more fully specified. In thisinstance I' have shown the outer end of the frame L as being thuselevated and lowered by means of vertical screw rods 0, arranged to turnin fixed nuts cl on the frame and in suitable bearings in carriage C andoperated by a hand-wheel e on the horizontal rod f through said rod f,bevel-gears g, also on said rod f, and bevel-gears c on screwn'ods c,the rod f being fitted. to turn in suitable bearings formed upon orsecured to carriage O. The yielding-spring movement is produced byinterposing spiral springs h between the under side of the frame and thetop of carriage O. The number of said screw-rods c and spiral springs 71is immaterial. Two of each, one on each side of the machine, arepreferably employed in practice. The upward movements of the outer endsof both frames L L are controlled within proper limits by means of thevertical guide-rods 'i j, fitted tight in the frames and loose in thecarriage C, so as to permit of the free vertical action of the ends ofsaid frames, and at the same time control their upward movements, asaforesaid. Each frame L L is provided with a series of verticaltransverse racking or rubbing blades L fitted in vertical transverseslotsL formed in the upper sides thereof. In practice they arepreferably made of hard wood and rounded at their upper edges, those atthe rear outer end of the frame L being, in practice, fittedsufficiently loose to admit of their easy removal to adjust the machineto different lengths of leather-as, for instance, if a shorter lengththan the last one is to be treated, one or more of said blades are removed, as required, to properly operate upon the bottom thereof, and fora longer length one or more would be added instead of removed.

The ends M' M of the leather M (see Figs. 1 and 2) are held in theslides or carriages I and K,between the beds 70 7c and theeccentric-rods Z Z thereof, the tops of said beds being preferablycorrugated transversely to facilitate holding said leather from pullingout, The eccentric-rods are fitted to turn in suitable bearings m mandare providedwith crank-levers n n, adapted to fit over the square ends Zthereof, and whereby they may be turned to clamp or release the leather,as required. 'The'cla'mp for holding the front end M of the leather isarranged to swivel, so as to automatically adapt itself toany'inequalities in the leather in the stretching operation, therebyevenly stretching the same and preventing the tearing thereof at suchplaces as will not stretch equally with the other portions. Said resultis effected by makin g the bed in two parts 10 the bottom of the upperpart 70 coming above the level of the guideways or tracks J, so as toswing around freely. The bottom part is slides in the track, and theupper part, which carries the eccentricrod Z and its bearings, ispivoted at its front end in a horizontal slot 70 to a pivot-bolt 7a,passed vertically through the parts, as is shown in Figs.- 1 and 2. 'Bythis construction it is obvious that the clamp may freely swinglaterally to accomplish the desired result.

The various parts of the machine herein before described constitute themechanism for holding the leather in position and for racking or rubbingthe bottom thereof to stretch the same. Y

' -I will'now describe the mechanism for taking up the slack produced bysaid stretching operation.

Upon the bottom of the bed k of slide or carriage K are formed orsecured one or more short longitudinal toothed racks 0. In practice twoare preferably employed, one at each side of the machine. Said racks 0engage with pinions p, secured to ahorizontal transverse shaft q,arranged under the same and fitted to turn in suitable bearings in'themain frame or bed A. To one end of'said shaft q, outside of the mainframe, is secured a large ratchet-wheel 7", whereby the shaft may beturned to operate the slide or carriage K forward and back through thepinions and racks, as hereinafter more fully specified. Saidratchet-wheelis in turn operated by power transmitted from the maindriving-shaftE (which operates the mainslide or carriage O, aspreviously specified) through the eccentric s on said main shaft,connecting-rod t, swinging arm a, pawl 12, pivoted lever w, and Weightedlever 00. The eccentric-rod t is pivoted to the lower end of swingingarm to, and the upper end of the arm fits in a longitudinal verticalslot a, formed in a horizontal plate 11, secured to the upright portionA of frame A. The arm is suspended on a transverse pin or lug uprojecting out from either side thereof and resting upon thetop of thesupporting-plate, thus permitting said upper end of the arm to movefreely back and forth in the slot u',above referred to. A constantforward pressure is imparted thereto by the Weight 00 through its leverw and pivoted lever w, the weighted lever being pivoted to the uprightframe A at 00 and pivoted with a lateral arm. :0 whose outer end bearsagainst the back side of one end of said pivoted lever 10, while theopposite end of the latter bears against the back side of the upper endof theswinging arm u, as is fully shown in thedrawings. The pawl 21 ispivoted at one end to the swinging arm,about midway between its 'en'ds,and its other or'free end is adapted to engage with the teeth of theratchet-wheel r, as is shown in Fig. 3. The lower end of the swingingarm and the outer end of the weighted lever are kept in their properpositions in operation by the guides y and y, respectively. The lever wis pivoted at w to the top of frame A By thus constructing the take-upmechanism it is obvious that a constant as well as a yielding forwardpressure is imparted against the upper end of the swinging arm. Inpractice said pressure is made sufficient by varying the size andposition of the weight :20 to hold the upper end of the arm withoutyielding up to a certain point in the stretching operation, the bearingat said upper end acting in this case as a pivot, while the lower' endthereof is swung forward and back by the action of the eccentric on themain shaft through the connections previously described. Each forwardmovement of the arm causes the pawl to move the ratchet-wheel onenotchforward, and in consequence the carriage or slide K is also movedforwardthrough the connections previously described, thereby keeping theleather taut as fast as it is stretched. The ratchet-wheel and otherparts are held against back motion, after having been thus movedforward, by a lock-lever z, pivoted to the main frame and engaging withthe teeth of the ratchet-wheel, as is shown in Fig. 3.

Although in practice I prefer the construction of the various parts asherein set forth, it will be understood that modifications in the shapeof said parts, such as would ordinarily be required under differentcircumstances, may be made without departing from the principle of myinvention.

The operation of applying a piece of leather and stretching the same bymeans of my improved machine is, in brief, as follows: The carriage K isfirst moved back nearly or quite up to the frame L, and the requirednumber of racking or rubbing blades are applied or removed to or fromframe L, according to the length of the piece of leather to be operatedupon. The ends of said leather are then clamped in the slides orcarriages I K, with the carriage I locked against forward movement andthe rear end of frame L properly adjusted vertically, as previouslydescribed, after which the machine may be started up in the usual way,thereby causing the racking or rubbing frames to be operated forward andback longitudinally with short and quick reciprocating movements to rackor rub the under side of the leather fastened over the same, and also tofeed forward the slide or carriage K, thus stretching said leather, andat the same time taking up the slack resulting from such stretching, thefeed.

movement causing the leather to be always drawn taut an d in a measureassist-ing in the stretching operation.

In starting up the machine the first forward movement of thereciprocating frames causes the bumpers I; (preferably of rubber) on thefront end of frame L to strike carriage K and at once move itintoposition for work, thus obviating any loss of time in commencin g thestretching operation. Up to the proper stretching limit of the leatherthe swinging arm 'u.,previously described,simply works back and forthfrom its top pivot like a clock-pendulum; but, after having beenstretched to its full extent or as much as required, the pressure of thepawl against the ratchet-wheel to turn the latter being greater than theresisting power exerted by the weight w, said weight is elevated by theforce of the eccentric s and the resistance of the ratchet wheel againstthe pawl, thus causing the upper end of the swinging arm to be forcedback and the pawl to operate without further turning the ratchet-wheel.Consequently the leather is also not further stretched. It will thus beobserved that the weight 0: acts as a governor on the machine to limitits powerof stretching the leather, and it will also be apparent that bychanging the size and position of said Weight the stretching capacitythereof may be varied at will and adjusted to a nicety.

After the leather has been stretched as far as permitted by theaforesaid governing mechanism,the machine, although allowed to continuein operation, has no effect upon the leather, as will be seen. No damageto either the machine or leather is therefore incurred if said machineis not at once stopped upon the completion of the stretching operation.

Said machine is strong and effective in use and may be convenient-1yoperated, thus enabling one workman to tend several machines at the sametime.

A superior quality of leather is produced, as the whole surface isevenly operated upon and stretched, and, furthermore, the saving inlabor and production is materially increased over the old form ofleather-stretching machines.

Having now fully described my invention, whatI claim therein as new, anddesire to secure by Letters Patent, is-

1. In a leather-stretching machine, the combination, with a horizontalcarriage fitted to slide in longitudinal stationary guideways or tracksand operated with reciprocating movements by connection with a crank oreccentric on the main drive-shaft, of two racking or rubbing framesarranged above said carriage and both pivoted at their inner endsthereto, the outer end of one frame having means whereby it may beadjusted vertically and the outer end of the other frame provided withmeans for exerting a constant upwardyielding pressure thereon, bothframes being also provided with a series of transverse racking orrubbing blades fitted in suitable slots in the upper sides thereof andwith means for controlling their upward movements, substantially as setforth.

2. In a leather-stretching machine, hori zontal racking or rubbingframes having adjustable and spring-yielding ends, substantially asdescribed, provided with a series of vertical transverse blades in theirupper sides, and having longitudinal reciprocating movements against theunder side of the leather, substantially as and for the purpose setforth.

3. In a leather-stretching machine, a horizontal supporting-carriagearranged under the bed of said machine and having reciprocatingmovements in longitudinal stationary guideways or tracks, and racking orrubbing frames mounted on said carriage, constructed substantially asspecified, in combination with an adjustable clamp fitted to slide inlongitudinal tracks at each side of the rear of the machine and providedwith means for holding the same in position, and a slide-clamp fitted toWork'in longitudinal tracks at each side of the front of the machine,having means connected therewith and with the driving mechanism forautomatically moving said clamp IIO IZO

forward with short intermittent movements, substantially as and for thepurpose set forth.

4. In a leatherstretching machine, the combination of carriage C, fittedto slide horizontally in the longitudinal guideways or tracks B B, andhaving reciprocating movements imparted thereto from crank E on the mainshaft through the connecting-rod F, with the frames L L, arranged abovesaid carriage G,'both pivoted at their inner ends thereto and providedwith a series of transverse vertical racking or rubbing blades L therear end of frame L being also provided with means for controlling itsupward movemen ts and for adjusting said frame vertically, and theforward end of frame L being provided with means for producing anupwardyielding pressure as well as for controlling the upward movementsthereof, substantially as and for the purpose set forth.

5. In a leatherstretching machine, the combination of the horizontallongitudinallyreciprocating carriage O with the frame L, pivoted at itsinner end to said carriage and having means at its outer rear end foradjusting the height thereof and for controlling its upward movements,substantially as and for the purpose set forth.

6. In a leather-stretching machine, the

combination of the horizontal longitudinallyreciprocating carriage Cwith the frame L, pivoted at its inner end to said carriage and havingmeans at its outer forward end for producing an upward-yielding pressureand for controlling its upward movements, sub-' stantially as and forthe purpose set forth.

7. In a leather -stretching machine, the combination of -thelongitudinal guideways or tracks H H, arranged above the bed A ateachside of the rear of the machine, with the slide or carriage I,fitted to slide therein and having means for holding it from movingtoward the front end of the machine, said racks upon the under sidethereof, the swivel arranged above and pivoted at its front end to saidbed-piece, the eccentric-rod Z, and bearings for said rod, incombination with the pinions p, horizontal transverse shaft q, andratchet-wheel r, substantially as and for the purpose set forth.

9. In a leather-stretching machine, the combination, with the toothedracks of carriage K, of pinions p, horizontal transverse shaft (1, andratchet-wheel r, substantially as set forth.

19. In a leather-stretching machine, the combination of slide orcarriage K, provided with a clamp device, substantially as described,with the ratchet-wheel 1', lock-lever z, swinging arm u, eccentric s,and the various connections and supports whereby short intermittentforward movements are imparted to said slide or carriage K,substantially as set forth.

11.. In a leather-stretching machine, the combination of slide orcarriage K, provided with a clamp device, substantially as described,with the ratchet-wheel r, lock-lever z, swinging arm-u, eccentric s,pivoted lever w, weighted lever 00, and the various con11ections andsupports whereby short intermittent forward movements are imparted tosaid slide or carriage K and the stretching capacity of the machinecontrolled, substantially as set forth.

12. In a leather-stretching machine, the ratchet-wheel 0,- provided witha lock-lever z, in combination with the pawl r, swinging arm u,suspended at its upper end from a fixed bearing, connecting-rod t,eccentric 8, main shaft E, and suitable supports and guides,substantially as and for the purpose set forth.

18. In a leather-stretching machine, the ratchet-wheel 4', provided withthe 1ock-lever z, in combination with the pawl Q1, swinging arm to,suspended from a fixed bearing at its upper end, eccentric-rod t,eccentric 8, main shaft E, pivoted lever w, weighted lever 03, andsuitable supports and guides, substantially as and for the purpose setforth.

BENJAMIN P. BRADFORD.

\Vitnesses:

A. A. BARKER, W. 1-3. NOURSE.

